Geyser’s revival of international significance

Revival of
Papakura Geyser in Rotorua’s Whakarewarewa geothermal
valley may be a world first, Bay of Plenty Regional Council
Chief Executive Mary-Anne Macleod says.

The Regional
Council manages the Rotorua Geothermal Field through the
Rotorua Geothermal Plan, which constrains use of the
resource to protect geothermal features.

“These
geothermal features have great local, national and
international significance and we acknowledge and recognise
the geothermal field as a taonga for tangata whenua,” Ms
Macleod says. “The revival of Papakura is great news not
only for Rotorua, but for all those who have been involved
over the years in monitoring and protecting these precious
assets.”

Bay of Plenty Regional Council Senior
Planner Bridget Robson says the Rotorua Geothermal Plan has
tightly managed the resource and it appears this action has
something to do with the geyser’s recovery.

“This
could be the first time in the world a management response
to a geothermal decline has had this type of result. Usually
when geysers have stopped erupting they have tended to stay
that way. What’s happening here suggests there is a big
lag period between changing use patterns and the geothermal
system responding. This will be of interest
internationally,” Ms Robson says.

Papakura was one
of Whakarewarewa’s most consistently active geysers and
has been dormant since March 1979 but is now “bubbling
away” with temperatures reaching boiling point and a
series of small eruptions spraying steam and water up to a
metre high.

“She is showing signs of being a geyser
again – this is very exciting.”

The Rotorua
Geothermal Plan came into effect in 1999, maintaining a
1.5km exclusion zone around Pohutu Geyser at Whakarewarewa,
a zone established in 1986 to halt the progressive decline
in surface geothermal activity. It saw the closure of
hundreds of bores in the city.

Following the closures
there were signs of recovery of geysers, springs and other
geothermal features. Groundwater levels bounced back fairly
quickly, Kuirau Park came back to life, Pohutu Geyser became
more active again – but the recovery of other surface
features was slower and Papakura, among other features,
remained dormant.

Regional Council became responsible
for managing the geothermal field in 1991 and developed the
Rotorua Geothermal Plan to protect the field and bring about
recovery. It sets out policies and rules for the use of
geothermal energy, puts a cap on the amount of geothermal
fluid and heat that can be used, promotes low-effect use and
includes ongoing monitoring.

Bay of Plenty Regional
Council will continue to work with the community, local
council, tangata whenua and the business sector to meet
needs, advance opportunities and preserve and enhance
geothermal resources.

Papakura showed no signs of
recovery until recently when routine monthly monitoring by
scientists from GNS, which carries out this work for the
regional council, showed increased levels of chloride
geothermal fluid, indicating increased fluid flows from deep
underground.

Ms Robson says the regional council will
continue to work with GNS to better understand the Rotorua
geothermal system and the impact of use of the resource.

The Rotorua geothermal field’s surface features and
unique ecosystems make it of high scientific and
conservation value internationally.

Bore numbers in
Rotorua increased significantly through the 1950s and 1960s
and in the 1970s

there was significant decline in surface
geothermal activity, especially at Whakarewarewa.

This
was believed to be the result of a reduction in the
geothermal aquifer water level, due to extensive withdrawal
of geothermal fluid from bores and no reinjection.

In
1980 the Minister of Energy and Rotorua District Council set
guidelines for drilling and use of geothermal energy in
Rotorua. A monitoring programme began in 1982 and a
taskforce was formed in 1983 to assess the extent of
geothermal fluid draw-off and investigate ways to reduce
it.

In 1986, prompted by increasing concern about the
effects of geothermal energy use on the geysers at
Whakarewarewa, the government ordered the closure of all
bores (106) within 1.5km radius of Pohutu Geyser and the
closure of all government department bores in Rotorua city.
Bore closures began in 1986 but most occurred during
1987.

The government also introduced a royalty scheme
for those extracting geothermal fluid across the field and
promoted reinjection of geothermal fluid back into the
field.

The number of bores dropped from 376 to 141,
resulting in a 30% drop in total mass withdrawal. A 50%
increase in deep bore reinjection reduced net withdrawal by
86% by about 1991.

Following the bore closures
geothermal groundwater levels increased, Kuirau Park came
back to life, Pohutu Geyser became more active again – but
the recovery of other surface features was slower and
Papakura, among others, remained dormant.

Whakarewarewa has the largest collection of surface
geothermal features in Rotorua with at least 65 recognisable
geyser vents although only about a handful will have been
active at any one time.

In Rotorua there are about
1550 geothermal features, ranging from steaming ground to
the spectacular
geysers.

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